[Feature #19236]

When building a large hash, pre-allocating it with enough
capacity can save many re-hashes and significantly improve
performance.

```
/opt/rubies/3.3.0/bin/ruby --disable=gems -rrubygems -I./benchmark/lib ./benchmark/benchmark-driver/exe/benchmark-driver \
	            --executables="compare-ruby::../miniruby-master -I.ext/common --disable-gem" \
	            --executables="built-ruby::./miniruby --disable-gem" \
	            --output=markdown --output-compare -v $(find ./benchmark -maxdepth 1 -name 'hash_new' -o -name '*hash_new*.yml' -o -name '*hash_new*.rb' | sort)
compare-ruby: ruby 3.4.0dev (2024-03-25T11:48:11Z master f53209f023) +YJIT dev [arm64-darwin23]
last_commit=[ruby/irb] Cache RDoc::RI::Driver.new (https://github.com/ruby/irb/pull/911)
built-ruby: ruby 3.4.0dev (2024-03-25T15:29:40Z hash-new-rb 77652b08a2) +YJIT dev [arm64-darwin23]
warming up...

|                    |compare-ruby|built-ruby|
|:-------------------|-----------:|---------:|
|new                 |      7.614M|    5.976M|
|                    |       1.27x|         -|
|new_with_capa_1k    |     13.931k|   15.698k|
|                    |           -|     1.13x|
|new_with_capa_100k  |     124.746|   148.283|
|                    |           -|     1.19x|
```